PERSONAL HABITS: Very clean, if somewhat ascetic (cold water scrubs each morning). Vegetarian. Munches his way through 80 pounds of clover a day, with, for variety, carrots and other vegetables suitable for a 20-year-old, two-horned black rhino.

PRESENT ABODE: Fred is living on a 35-acre site with all amenities in a highly desirable area of central London - but in extremely straitened circumstances.

Fred is for real. So is the appeal being launched on his behalf by his landlords, the management of London Zoo. Prospective parents might balk at the thought of keeping Fred tethered to the garden gate, or of scrubbing his back in the bath. But there is no question of that - he's not actually being evicted. All he wants is for someone to help keep him in the style to which he has become accustomed, because London Zoo is broke and looking for help wherever it can find it.

Like every household, the zoo is suffering the effects of inflation; but its problems are compounded by the fact that it has more than 8,000 mouths to feed. Its annual shopping list for food alone includes 40,000 bananas, 14 tons of herring, and 38,500 eggs - not to mention a regular supply of blackcurrant jam sandwiches, which are essential if the giant tortoises are to be persuaded to swallow their daily dose of vitamins.

The Animal Adoption Scheme, launched in June, is the zoo's way of encouraging the public to help pay for the soaring costs that have taken it more than $:1.5 million ($2.4 million) into the red. This year, for the first time in its long history, the zoo has been forced to ask the government for aid. It is, in fact, the only major national zoo that does not already receive regular and substantial government subsidies.

Right now, Fred and his neighbors are living on a temporary government grant of $:1 million, while they wait for a three-man government-appointed team to report on the zoo's finances and make recommendations on cutting costs and increasing revenue. One solution they will not be considering will be raising the cost of admission, which is already so high that it is seen as a major reason for the 20 percent slump in zoo visitors last year. It costs a family with two children $:10 for a day out at the zoo - not counting popcorn, ice cream, pony rides, and souvenirs.

Besides, the zoo's management believes that the days when the zoo could survive on takings at the gate are long gone. It feels that the government must find the money to bail out what amounts to a national institution, and one of London's most popular tourist attractions.

Given the zoo's primary function as a major scientific research center and its concern to educate, rather than simply entertain the public, there are not many financial options open to it. It cannot, as some of its critics have suggested, ''Go Disneyland,'' to help bring in the visitors. The sideshows and razzmatazz of a funfair-type zoo would run completely counter to the zoo's scientific aims.

Jonathan Griffin, its commercial manager, explains: ''Our aim is the advancement of zoological knowledge, breeding, and scientific study. Not only does it cost money, but it is not of direct interest to the public. That is the dilemma at the root of our financial problem.''

So while the government's three wise men consider how the zoo can avoid bankruptcy, its inmates are up for adoption - and there is no shortage of takers. Individuals, families, and schools have jumped at the chance of buying $ :30 ($48) ''shares'' in the animals. What they get for their money depends entirely on how they want to invest it.

A sea lion costs $:2,000 ($3,240) a year to maintain, an elephant $:5,000 ($8 ,100) and a brown bear $:1,500 ($2,430), what with food, water, bedding, and vitamins. So, a brown bear = 50 shares a year. A fruit bat, at only $:30, is a better bargain.

In other words, prospective parents can get a whole fruit bat for their money , or settle for a couple of spots on a leopard, or perhaps a lion's mane, for the same amount. In return, the adopter receives a certificate and concessionary tickets to the zoo, plus the knowledge that his charge will not - for a year at least - have to suffer a drop in living standards. The most generous gift so far has come from a family living in New York, which has fully adopted a rare gray seal for four years - at a cost of $:1,000 a year.

But given the British propensity for backing the underdog, the least engaging species are proving the most popular: the two-toed sloth, the warthogs, and aardvark, the lappet-faced vulture, and the largest rodents in the world, the capibaras, are already fully adopted. The pygmy hippos and an assortment of bats and toads are also going fast, but nobody seems to want such noble old zoo favorites as brown bears, lions, small monkeys, the North American bison, . . . and Fred.

A Mrs. and Miss Bat have adopted one of the fruit bats, and a Portsmouth-based submarine, HMS Opossum, has adopted the striped possum.

One young man adopted no less than three Surinam toads - as a surprise for his mother. He made no bones about it, according to Sarah Chivers, the lady in charge of the program: ''He simply asked for 'something truly revolting, like mum,' and promptly had the adoption certificate dispatched direct to her.''

British companies are also being roped in to help the zoo out of its financial plight, through a sponsorship program whose proceeds go toward conservation, education, and research. This plan, which costs $:500 a year, enables them to sponsor a whole group of animals and to have a plaque, bearing their name, displayed outside the enclosure of the animal they have chosen.

So far, the two programs between them have raised about $:20,000 - a drop in the ocean as far as the zoo's finances are concerned. But the zoo has succeeded in publicizing its plight and in drawing the government's attention to the importance the people of London attach to their zoo.